Message-ID: <4FDAA5D5.7080606@hitachi.com>
Date: Fri, 15 Jun 2012 12:02:45 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Organization: Hitachi, Ltd., Japan
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        yrl.pp-manager.tt@hitachi.com
Subject: Re: [RFC][PATCH 02/13 v2] ftrace: Consolidate arch dependent functions
 with list function
References: <20120612224327.426900129@goodmis.org> <20120612225424.495625483@goodmis.org>
In-Reply-To: <20120612225424.495625483@goodmis.org>
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(2012/06/13 7:43), Steven Rostedt wrote:
> From: Steven Rostedt <srostedt@redhat.com>
> 
> As the function tracer starts to get more features, the support for
> theses features will spread out throughout the different architectures
> over time. These features boil down to what each arch does in the
> mcount trampoline (the ftrace_caller).
> 
> Currently there's two features that are not the same throughout the
> archs.
> 
>  1) Support to stop function tracing before the callback
>  2) passing of the ftrace ops
> 
> Both of these require placing an indirect function to support the
> features if the mcount trampoline does not.
> 
> On a side note, for all architectures, when more than one callback
> is registered to the function tracer, an intermediate 'list' function
> is called by the mcount trampoline to iterate through the callbacks
> that are registered.
> 
> Instead of making a separate function for each of these features,
> and requiring several indirect calls, just use the single 'list' function
> as the intermediate, to handle all cases. If an arch does not support
> the 'stop function tracing' or the passing of ftrace ops, just force
> it to use the list function that will handle the features required.

Ah, I see. so even if the arch doesn't support passing ftrace_ops in
mcount trampoline, this ensures that the correct ftrace_ops should
be passed to the handlers.

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Thank you,


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
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